Publish Time: 2022-07-16 Origin: Site
The working characteristic of the air DTH hammer is to use compressed air as the power (including the compressed air containing foam), and the energy of the compressed air generated by the compressor is passed through the energy conversion device of the DTH hammer.
How does the DTH hammer bit work?
What are the classifications of DTH hammer bit?
What are the job requirements for the DTH hammer bit?
The drill bit of the DTH hammer bit can drill a hole larger than the outer diameter of the casing at the bottom of the casing, so that the casing can follow up smoothly; when the drill is lifted, the reaming bit can be easily retracted, so that the entire drilling tool can be Lift out of the casing. The DTH hammer bit consists of a DTH hammer, a guide, an eccentric reaming drill bit, a center drill bit, an eccentric sheath, a conical drill bit for sand layers and a casing shoe. A centralizer, a powder taking pipe and a powder discharge hood can be attached as required, or a double-wall drill pipe plus a positive and negative joint with a packer can be used for central sampling drilling.
DTH hammers used in hydrological water wells are also divided into hydraulic DTH hammer drilling (usually called hydraulic hammer) and pneumatic DTH hammer drilling (usually referred to as DTH hammer) according to the different circulating media driving the bottom impactor. hammer). There are SC-150 series of hydraulic DTH hammers, which are mainly used in the drilling of bedrock hydrological wells with a diameter of 150-260mm. Pneumatic DTH hammer is a drilling method in which compressed air is used as a circulating medium and at the same time as the driving force of the bottom impactor, which is called DTH hammer drilling. It is an excellent drilling method with high efficiency. The efficiency of hard rock drilling is several to dozens of times higher than that of rotary drilling, so it has developed rapidly in hydrological wells and other drilling industries.
1. Wind pressure
The impact frequency and impact energy of the DTH hammer bit are related to the wind pressure. When the wind pressure is increased from 0.6MPa to 1.03MPa, the drilling efficiency can be doubled. The wind pressure required by the low-pressure DTH hammer is 0.5-0.7MPa, and the wind pressure required by the high-pressure DTH hammer is 1.2-2.2MPa.
When drilling with a DTH hammer, in addition to the wind pressure required for the normal operation of the DTH hammer, the pressure increased with the increase of the drilling depth and the pressure of the water column below the water level is overcome. In production, the method of series supercharger is often used to increase the wind pressure.
2. Air volume
The drilling speed of the DTH hammer bit is fast, and the debris particles produced per unit time are large and heavy, and a large air volume is required to make the bottom of the hole clean. The DTH hammer itself also has a certain rated air volume to work properly. For example, the rated air volume of W-200 DTH hammer is 10～20m3/min.
Judging from the test drilling situation, the DTH hammer can only play a good role when the upward and return wind speed in the well is greater than 15m/s. Therefore, the air volume is required to ensure that the upward and return wind speed in the well is greater than 15m/s.
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